Our take: This fancy pull-up bar is great for home (or hotel) workouts because it mounts in doorways securely but without leaving a mark. Three different grip options allow you to work your complete upper body, and it also doubles as a foot support for crunches or a platform for push-ups and dips. Alas, it's a bit clunky and won't fit well in smaller duffles or suitcases, so it should be saved for longer trips that require bigger bags. Plus, it won't fit in all types of doorwaysand once you've calibrated it to fit in one, it takes some rejiggering to set it up for anything that's a different size.

Bottom line: This is a great upper-body workout for the price, but it lacks portability and total body–conditioning potential.

Our take: The packability of these dumbbells and ankle weights makes them a cinch to tuck in your luggage (the kit is about the size of a textbook). When youre ready to work out, fill the plastic dumbbell ends with water (it takes only a couple of minutes) and attach them to the light-weight bar for up to 16 pounds of resistance per dumbbell (4 pounds for each ankle weight). Problem is, the set doesnt include a workout DVD or booklet, though there are exercises on the Web site.

Bottom line: You cant get much simpler than just adding water. But the lack of workout guidance makes this kit best for people who already have a regular weight routine.

Our take: This high-end kit pairs nylon suspension cables with a variety of handles and removable anchors, so you can hook it up almost anywhereto a door, tree branch, or any other elevated fixture (think gymnastic rings hanging from the ceiling). The whole kit weighs less than two pounds and comes with a small storage bag and exercise DVD, and you can change the resistance and difficulty simply by shifting the position of your body.

Bottom line: You can definitely get an effective workout almost anywhere with this system, but the higher price might make it impractical for someone who already has a gym membership, or can hit the hotel weight room free of charge.

Our take: We love the simplicity of this compact, low-priced kit. With three pieces of resistance tubing, it fits easily into carry-on luggage. It also includes a DVD with beginner, inter-mediate, and advanced full-body workouts, a helpful exercise poster, and a door connector and ankle straps for lower-body moves. The workout itself is well-explained and covers all major muscle groups. The only drawback: If you dont like working with bands, this is not the kit for you.

Bottom line: Our favorite of the four kits, its well-made, inexpensive, and practical enough to keep you moving during weekends (or weeks) away.